Ghosts and membrane fluidity

Does anyone have any experience with measuring membrane fluidity in
erythrocyte ghosts using fluorescence polarization? Specifically, are
there any special tricks to preparing ghosts for this purpose? I've been
trying to reproduce earlier literature results (as well as some of my
own) on the membrane-disordering effects of some simple acids without any
luck. A wash with PBS/lyse with hypotonic buffer/wash with PBS approach
is being used.
Any help would be greatly appreciated! Thanks.
Jan Palaty
Faculty of Pharmacy